Treatment of cardiac arrhythmia should be specifically aimed at symptom control or reduction in the risk of sudden cardiac death. Until recently, a limited number of antiarrhythmic drugs were available to the practicing physician, but during the last four years, seven new ones were approved. However, these drugs are complex and have different mechanisms of action and potential for adverse effects, so the safety of therapy with them continues to be debated. Although there is little doubt that many of the new drugs (particularly flecainide [Tambocor] and encainide [Enkaid]) are highly effective in suppressing ventricular premature complexes, they should be used with caution, since they also carry a potential for worsening arrhythmia (proarrhythmic effect) and congestive heart failure. Since suppression of arrhythmia has not yet been proven to reduce mortality, care must be taken in evaluating the risk-benefit ratio when prescribing therapy, particularly for patients with less malignant arrhythmias. Careful evaluation of the effects of treatment in individual patients is indicated whenever antiarrhythmic drugs are used. Until important mortality trials have been completed (eg, the Cardiac Arrhythmia Suppression Trial), therapy should be conservative and reserved for patients with severely symptomatic or malignant arrhythmias.